Method and apparatus for cracking hydrocarbon oils



Nov. 25, 1930.

R. J. DEARBORN 1,783,010

HETHODAND APPARATUS FOR CRACKING HYDROGARBON OILS Filed Jan. A19, 1928 Patented Nov. 25, 1930 UNITED s'ra'rEs` PATENT OFFICE aleman .'r. DEAEBOEN, or SUMMIT, NEW JERSEY, salon-oa ro THE 'rExas cou- PANY, F NEW YORK, N. Y., A CORPQRATIONOF DELAWARE :METHOD AND APPARATUS FOR QRACKING HYDBOCABBON OILS Application -ledIanuary 19, 19248. Serial No. 247,882.

This invention relates to the conversion of higher boilingpoint hydrocarbon oils into lower boiling point products, and has special reference to a cracking process and apparatus Al, of the so-called oil and drumtype, in which the oil is decomposed or cracked by rapidly raisin the temperature thereof in transit throug a heating coil, and then delivering it into an enlarged drum orchamber in which cracking temperatures and pressures are maintained.

One ofthe objects of this invention is to provide a method and system of this general character in which the bulk ofthe heat employed for the cracking operation is imparted to the oil in transit through the heating coil, while the maintenance or the attainment of the desired cracking temperature is' eifected in a heat-insulated enlarged drum by aux 2o iliary heat imparted by means of vpipe coils enclosed within the drum, and through which coils, highly heated hydrocarbon vapors and gases, hydrogen or other vaporous or 'gaseous mediums are passed.

More specifically, however, an object of this invention is to provide a cracking process and stem'of the above indicated type, wherein t e desired cracking temperature mlthe drum is effected by passing the highly heated vapors of a vapor-phase cracking process through coils disposed therein and in indirect contact with the bod of oil in the drum, l

Another object o the invention is to suspend the auxiliary heating coil from a remova5 able cover of the drum, so that it can be readily removed for cleaning and inspection pur- These'and other objects of this invention, and features by means of which they are attained will be more fully understood from the following description of the process in connection with the preferred embodiment of the a aratus as illustrated in the sin le iigure oi) he accompanying drawing, which is a diagrammatic view of an `apparatus orvsystem constructed in accordance wlth the present invention. 1

Referring to the drawing the system shown comprises an elongate heating coil 1 1 of restricted cross-section for heatingthe oil `1ine 3 between the-coil 1 in transit, by means of a suitable furnace 2 which is fired byI a burner 2, disposed below y drum 4 is heat-insulated by means of lagging 5. The heated oilemerging from the coil l1 is conducted through a heat-insulated pipe 3 and is delivered into the bottom of the drum 4. The heated oil emerging from the coil 1 may have a'temperature, depending upon the charging stock, varying from 750 F. to 950 F., or even higher, but more `frequel'itly the temperature is maintained at approximately 850 F. Pressure is preferably maintained in the system, and may range from 100 to several hundred pounds depending upon conditions. A valve 7 may be interposed in the and the drum 4, if desired, and may be utilized either for reducing the pressure in the drum or merely for einer ency purposes in case of fire. Ordinarily,`th1s valve 7 will be fully open. A draw-off line v8 havingla valve 9 is provided in the bottom head of the drum 4.

A heat-insulated vapor line 10 permits the passage of the vapors from the drum' 4 to the separator 12, wherein a separation 4of the lighter and heavier constituents may be effected. f The lighter constituents, emerging as a vapor from the upper end of the -separator 12, pass through apipe 13 and into a Water-cooled condenser 16 where the vapors are condensed and then pass through pipe 19 to enter the receiving tank is provided with a gas outlet 21 having a valve 22, and a discharge outlet 23 havingfa valve 24. The heavier constituents, vcondensed in the separator 12, are drawn oil' by means of pipe14 and valve 15, and may. be

-used for recycling to the heating coil or otherwise, as desired.

For the purpose of assisting in maintaining the desired cracking temperature in the drum 4, an auxiliary vapor-plfase converter 300i` any type suitable is employed. As illustrateld, this converter is of a form similarf to that of the heating coil 1, thatvis, an elongated coil of restricted cross section, that 20 which is highly heated by a suitable furnace 31 fired by a burner 32 disposed below it.

The vapors in the converter coil are preferably subjected to pressure and to a high temperature, for example, from 1000 F. to 1300o F., whereby cracking in the vapor phase is effected therein. A temperature of around 110()o F. will ordinarily be adequate.

The issuing hot cracked vapors and gases are passed through a heat-insulated line 35 to a vertically disposed coil 38, which is completely enclosed within the drum 4 and is suspended from the removable cover 4".

l'The construction and arrangement is such that upon releasing the attaching means of the removable cover 4", the cover and the coil 38 may be removed as a unit from the drum, to facilitate the cleaning operation.

The coilV 38, being subjected to the high temperatures of the cracked vapors and gases emerging from the converter 30, which continuously pass through it, thereby constitutes a heating element for the body of heated liquid contained in drum 4, in which the coil 38 is wholly or partially submerged. Thus the coil imparts additional heat to the hot oil in the drum suliicient in quantity and degree to maintain the desired cracking temperatures therein by compensating for heat losses incident to radiation, decomposition and distillation, or even to raise the temperature slightly above that'of the heating coil 1 to attalna somewhat higher cracking ternperature, if desired.

' Obviously, the bulk of the heat is imparted to the oil in transit through the heating coil 1, but the heat abstracted from the auxiliary vapor-phase operation is utilized for the regulated maintenance of whatever cracking temperature is determined upon for the oil in the cracking drum. This regulation is accomplished by the proper control of the vapor-phase operation, as to temperature or speed'of ow of theproducts passing therethrough.

The highly heated vapors emerging from the coil 38 pass through a heat-insulated pipe 39, provided with a pressure-reducing valve 40, and are discharged into a separating and carbon receiving drum 43, which is heat-insulated by means of lagging 44. A draw-0H 41 having a valve 42 is provided at the bottom of drum 43 for the discharge for heavy tar and carbon.

The vapors emerging from the top of drum 43 are conducted through a heat-insulated pipe into a separator 51 wherein a separation of the lighter and heavier constituents may be eiected. The lighter constituents, emerging as a vapor from the upper end of the separator 51, pass through pipe 54 into a water-cooled condenser 55, where the vapors are condensed. The distillate passes through a' pipe 57 into a receiving tank 59, which is provided with a gas outlet having a valve 61 and a discharge outlet 62 having a valve 63. The heavier constituents condensed in separator 51 are drawn oif by means of pipe 52 and valve 53, and may be used for recycling or otherwise, as desired.

The system and method of operation set forth provides a simple and effective way of maintaining any desired cracking temperature in the liquid-phase cracking drum, while at the same time conserving the heat of a vapor-phase cracking operation which would otherwise'be Wasted. Moreover, the removability of the auxiliary heating coil contributes to facility in the cleaning operation.

Although the invention, as set forth for illustrative purposes, embodies more or less specic details of construction and operation, it should be understood that many variations and modifications may be effected therein without departing from the spirit and scope of the invention in the main. Therefore, only such'limitations should be imposed as are indicated in the appended claims.

What I claim is:

1. A process of converting higher boiling point Yhydrocarbon oil into lower boiling point products which comprises passing the oil through a heating coil of restricted cross section, heating the oil in transit to substantially a cracking temperature, delivering the heated oil into a cracking drum where a bod of oil collects, simultaneously cracking oil in the vapor-phase at a relatively high cracking temperature, and passing the cracked vapors and gaseous products thereof in indirect contact with said body of oil to maintain a cracking temperature therein and effeet cracking of the oil in the liquid phase.

2. A process `of converting higher boiling point hydrocarbon oilinto lower boiling )point products which comprises heating a stream of oil to substantially a cracking temperature in its passage through a heating coil of restricted cross section, delivering the heated oil into an enlarged cracking drum where a body of oil collects, maintaining a cracking temperature in said body of oil by passing the hot cracked products of a simultaneously operated vapor-phase cracking operation in indirect contact 4therewith, and regulating the temperature of said oil body 'by controlling the operation of the vaporphase cracking operation.

3. ApparatusI for converting higher boiling point hydrocarbon oils into lower boilin point products, comprising an elongated heating coil through which oil passes in transit and is heated, a heat-insulated drum connected with the heating coil wherein a body of hot oil collects, a vapor-phase con,- verter, an vauxiliary coil enclosed within the said drum and submergedin the hot oil therein and means for conducting the vapor-phase cracked products 'from said converter through said auxiliary coil to impart heat tothe body of hot oil and maintam it at a cracking temperature.

4. Apparatus for converting higher boiling point hydrocarbons into lower boiling point products, comprising a heating coil of l restricted cross ysection for heating oil in transit therethrough to a high temperature, an insulated enlarged crackin drum con-- nected thereto for receiving the cated oil in a body, an outlet line from the upper portion `of the drum for passing of vapors-and an outlet 4line from the lower portion of the drum for passing' olf the liquid portion, a Ivapor phase cracking converter having connected thereto a coil removably suspended within the drum and means for passing vaporous or gaseous products from said converter at a high cracking temperature throughthe suspended coil to therebyjniaintain the oil body at a cracking temperature.

witness whereof I have hereunto set my hand this 6th day of Janna 1928.

` R. J. DEA BORN. 

